On 21 October 2005, the full federal court of Australia handed down Fresenius Medical Care Australia Pty Limited v Gambro Pty Limited  FCACF 220 .
This case is worthy of study by patent practitioners and patentees alike. Their honours Wilcox, Branson and Bennett JJ provide a good treatise on the construction of claims for the purposes of infringement.
Gambro is the exclusive licensee of Australian patent no. 595423. As such it had the standing to sue Fresenius for infringement, which it did. In the lower court, the judge found that Fresenius had infringed a number of the claims and that the patent was valid. This case concerns the appeal by Fresenius against this judgement. Fresenius' appeal failed.
The reasoning is turgid. However, the full court made some constructive points in connection with claim interpretation for the purposes of deciding infringement and these are discussed below.
The "Essence" of the Invention:
Fresenius objected to the manner in which the primary judge had interpreted the claims. In an apparent attempt to identify essential features of the claims, the primary judge identified some "essence" of the invention, ie " the use of dry powder in a vessel and its dissolution by the introduction of water into the vessel to produce a saturated (and so constant) concentrate fluid that was then withdrawn from the vessel and then dealt with in the customary way by the relevant machines." In order to ascertain the scope of a claim, it is neccessary to determine the essential features or integers of that claim. In support of this strategy, the primary judge cited Commonwealth Industrial Gases Ltd v MWA Holdings Pty Ltd (1970) 180 CLR, where it was held that the interpretation of the specification and claims is to be undertaken having regard to the essence of the invention. His honour decided that the essential integers of a claim are those which are necessary for "the essence of the invention". Other integers were classified as inessential and thus not influencing the scope of the claims.
Their honours held that applying such a principle on its own is erroneous. They held that the subject matter of the claims must be determined. Reference to the specification may be made to understand the context of the claim wording and thus whether or not integers were essential. In this regard, their honours concurred with Gambro in that the claims are to be read in the context of the specification not only when ambiguity exists in the claims. However, their honours did point out that doing so does not permit the adding of integers to the claims.
In Catnic Components Limited v Hill & Smith Limited  RPC 183, the specification is to be read in the light of the common general knowledge before the priority date. The essential features are to be determined in the context of the then existing knowledge, as the patent is addressed to those skilled in the art. The specification serves as a tool for such persons to identify the essential features of the claims.
The analysis of whether or not claim 4 was infringed raised some issues worthy of discussion. The claim included the words: "a vessel containing a powder concentrate, said vessel including an inlet at the top thereof and an outlet at the bottom thereof;... ".
The "outlet" was interpreted, after consulting dictionaries, as an opening or passage by which anything is let out, including a vent or exit. Armed with this interpretation, the primary judge recognised that the Fresenius device did not have an opening at the bottom of the relevant vessel. In short, the Fresenius device is a column within a vessel. Concentrate leaves the column at the bottom of the column, which is at the bottom of the vessel. The concentrate enters a tube that conducts the concentrate to an opening at the top of the vessel. The primary judge held that the precise location of a break in the skin of the vessel is functionally immaterial. He reasoned that there was a fundamental lack of advantage of the Fresenius device over the vessel of claim 4.
In setting out the error in this approach, their honours explained that one does not investigate whether the allegedly infringing article is the same in substance and effect as the disclosures of the specification and claims. The form and wording of the claim are determinative. The primary judge impermissibly construed the claim with an eye to the allegedly infringing article.
Their honours held that when the claim is read in the light of the specification as a whole, including the figures, there can be no doubt that the outlet of the claim is an outlet both located at the bottom of the vessel and an outlet from the bottom of the vessel. By looking at the functionality of the Fresenius device, the primary judge had substituted a mechanical equivalent of an essential integer of the claim. This is not permissible for the purposes of ascertaining novelty or infringement.
For Patentees and Practitioners:
Claims should be drafted very carefully with a clear view of the features of an invention for which protection is sought. The clear meaning of the words in the claim will be taken as defining the scope of protection sought. Whether or not particular features are essential or not cannot be decided based on the functional "essence" of the invention. Rather, a reading of the specification with reference to the drawings in the shoes of the nominally skilled person is determinative of whether or not particular features are essential.